In recent years, the development of renewable energy has increased due to concern over the availability of fossil energy sources as well as environmental concerns. Among the different kinds of renewable energy sources, solar energy is the most abundant. Accordingly, there has been intensive research on how to collect solar energy and transform it into electricity. Among the different techniques proposed, photovoltaic (PV) cells are well known in the art and have been extensively developed in order to increase their efficiency and lower their cost.
In particular, concentrated photovoltaic (CPV) cells are known to be cheaper to manufacture than a standard photovoltaic type system providing the same amount of power. This is due to the fact that concentrated photovoltaic cells use lenses to focus the solar light on a PV surface, which is smaller due to the light concentration. Accordingly, the area and material required is reduced.
At high concentration ratios of the solar light, for instance, more than 500 times, cooling of the photovoltaic cell is required. This is due to the fact that PV cells are less efficient at higher temperatures and due to the possibility of the PV cells being damaged by very high temperatures.
In order to cool down the PV cells, passive cooling, such as a heat dissipater, becomes complicated and, therefore, costly. As an alternative, it is known to use an active cooling solution in which some medium, like water or oil, is used for cooling down the cell. In this approach, the cooling medium is heated and either directly used, for instance, as hot water, or used to run a generator for electricity production. In the latter case, the efficiency of the electricity generation process is rather low.
More specifically, a typical CPV cell can be sized between 0.25 cm2 and 1 cm2. Assuming a concentration ratio of 500, it can be estimated that about 5 to 18 watts are wasted in heat. This is roughly on the same order of magnitude of the energy transformed into electricity by the CPV cell.